Also, perlfaq8 has one entry titled:

How do I timeout a slow event?

Use the alarm() function, probably in conjunction with a signal handler, as documented in "Signals" in perlipc and the section on ``Signals'' in the Camel. You may instead use the more flexible Sys::AlarmCall module available from CPAN.

Be careful when implementing signals. Take a look at the %SIG section of the perlvar POD for some clues and warnings. Remember that the alarm signal, like other signals, can't be trapped with eval directly, it will exit unconditionally. You have to catch the signal in %SIG and die() to make it catchable. Something like:

   $SIG{ALRM} = sub { die 'timeout' };
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Another possibility is something like the following (untested) code snippet:

   use strict;
   use IO::Select;

   open(CMD, "shell_cmd|") or die $!;
   unless(IO::Select->can_read(1) ) { die "timed out!"; }
   print while(sysread(CMD, $_, 4096));
   close(CMD);
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For capturing the output, you probably want (my old favorite), IPC::Open3, which gives you STDIN, STDOUT, and STDERR. Be wary of the race conditions though, read the POD and examples very carefully. Good luck!